t: use git-show-ref(1) to check for ref existence

Convert tests that use `test_path_is_file` and `test_path_is_missing` to
instead use a set of helpers `test_ref_exists` and `test_ref_missing`.
These helpers are implemented via the newly introduced `git show-ref
--exists` command. Thus, we can avoid intimate knowledge of how the ref
backend stores references on disk.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1430-bad-ref-name.sh

@@ -205,8 +205,9 @@ test_expect_success 'update-ref --no-deref -d can delete symref to broken name'
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref msg &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
+	test_ref_exists refs/heads/badname &&
 	git update-ref --no-deref -d refs/heads/badname >output 2>error &&
-	test_path_is_missing .git/refs/heads/badname &&
+	test_ref_missing refs/heads/badname &&
 	test_must_be_empty output &&
 	test_must_be_empty error
 '
@@ -216,8 +217,9 @@ test_expect_success 'branch -d can delete symref to broken name' '
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref msg &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
+	test_ref_exists refs/heads/badname &&
 	git branch -d badname >output 2>error &&
-	test_path_is_missing .git/refs/heads/badname &&
+	test_ref_missing refs/heads/badname &&
 	test_i18ngrep "Deleted branch badname (was refs/heads/broken\.\.\.ref)" output &&
 	test_must_be_empty error
 '
@@ -225,8 +227,9 @@ test_expect_success 'branch -d can delete symref to broken name' '
 test_expect_success 'update-ref --no-deref -d can delete dangling symref to broken name' '
 	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref msg &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
+	test_ref_exists refs/heads/badname &&
 	git update-ref --no-deref -d refs/heads/badname >output 2>error &&
-	test_path_is_missing .git/refs/heads/badname &&
+	test_ref_missing refs/heads/badname &&
 	test_must_be_empty output &&
 	test_must_be_empty error
 '
@@ -234,8 +237,9 @@ test_expect_success 'update-ref --no-deref -d can delete dangling symref to brok
 test_expect_success 'branch -d can delete dangling symref to broken name' '
 	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref msg &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
+	test_ref_exists refs/heads/badname &&
 	git branch -d badname >output 2>error &&
-	test_path_is_missing .git/refs/heads/badname &&
+	test_ref_missing refs/heads/badname &&
 	test_i18ngrep "Deleted branch badname (was refs/heads/broken\.\.\.ref)" output &&
 	test_must_be_empty error
 '
@@ -245,8 +249,9 @@ test_expect_success 'update-ref -d can delete broken name through symref' '
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...ref" &&
 	test-tool ref-store main create-symref refs/heads/badname refs/heads/broken...ref msg &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/badname" &&
+	test_ref_exists refs/heads/broken...ref &&
 	git update-ref -d refs/heads/badname >output 2>error &&
-	test_path_is_missing .git/refs/heads/broken...ref &&
+	test_ref_missing refs/heads/broken...ref &&
 	test_must_be_empty output &&
 	test_must_be_empty error
 '
@@ -254,8 +259,9 @@ test_expect_success 'update-ref -d can delete broken name through symref' '
 test_expect_success 'update-ref --no-deref -d can delete symref with broken name' '
 	printf "ref: refs/heads/main\n" >.git/refs/heads/broken...symref &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
+	test_ref_exists refs/heads/broken...symref &&
 	git update-ref --no-deref -d refs/heads/broken...symref >output 2>error &&
-	test_path_is_missing .git/refs/heads/broken...symref &&
+	test_ref_missing refs/heads/broken...symref &&
 	test_must_be_empty output &&
 	test_must_be_empty error
 '
@@ -263,8 +269,9 @@ test_expect_success 'update-ref --no-deref -d can delete symref with broken name
 test_expect_success 'branch -d can delete symref with broken name' '
 	printf "ref: refs/heads/main\n" >.git/refs/heads/broken...symref &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
+	test_ref_exists refs/heads/broken...symref &&
 	git branch -d broken...symref >output 2>error &&
-	test_path_is_missing .git/refs/heads/broken...symref &&
+	test_ref_missing refs/heads/broken...symref &&
 	test_i18ngrep "Deleted branch broken...symref (was refs/heads/main)" output &&
 	test_must_be_empty error
 '
@@ -272,8 +279,9 @@ test_expect_success 'branch -d can delete symref with broken name' '
 test_expect_success 'update-ref --no-deref -d can delete dangling symref with broken name' '
 	printf "ref: refs/heads/idonotexist\n" >.git/refs/heads/broken...symref &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
+	test_ref_exists refs/heads/broken...symref &&
 	git update-ref --no-deref -d refs/heads/broken...symref >output 2>error &&
-	test_path_is_missing .git/refs/heads/broken...symref &&
+	test_ref_missing refs/heads/broken...symref &&
 	test_must_be_empty output &&
 	test_must_be_empty error
 '
@@ -281,8 +289,9 @@ test_expect_success 'update-ref --no-deref -d can delete dangling symref with br
 test_expect_success 'branch -d can delete dangling symref with broken name' '
 	printf "ref: refs/heads/idonotexist\n" >.git/refs/heads/broken...symref &&
 	test_when_finished "test-tool ref-store main delete-refs REF_NO_DEREF msg refs/heads/broken...symref" &&
+	test_ref_exists refs/heads/broken...symref &&
 	git branch -d broken...symref >output 2>error &&
-	test_path_is_missing .git/refs/heads/broken...symref &&
+	test_ref_missing refs/heads/broken...symref &&
 	test_i18ngrep "Deleted branch broken...symref (was refs/heads/idonotexist)" output &&
 	test_must_be_empty error
 '

t/t3200-branch.sh

@@ -25,7 +25,7 @@ test_expect_success 'prepare a trivial repository' '
 
 test_expect_success 'git branch --help should not have created a bogus branch' '
 	test_might_fail git branch --man --help </dev/null >/dev/null 2>&1 &&
-	test_path_is_missing .git/refs/heads/--help
+	test_ref_missing refs/heads/--help
 '
 
 test_expect_success 'branch -h in broken repository' '
@@ -40,7 +40,8 @@ test_expect_success 'branch -h in broken repository' '
 '
 
 test_expect_success 'git branch abc should create a branch' '
-	git branch abc && test_path_is_file .git/refs/heads/abc
+	git branch abc &&
+	test_ref_exists refs/heads/abc
 '
 
 test_expect_success 'git branch abc should fail when abc exists' '
@@ -61,11 +62,13 @@ test_expect_success 'git branch --force abc should succeed when abc exists' '
 '
 
 test_expect_success 'git branch a/b/c should create a branch' '
-	git branch a/b/c && test_path_is_file .git/refs/heads/a/b/c
+	git branch a/b/c &&
+	test_ref_exists refs/heads/a/b/c
 '
 
 test_expect_success 'git branch mb main... should create a branch' '
-	git branch mb main... && test_path_is_file .git/refs/heads/mb
+	git branch mb main... &&
+	test_ref_exists refs/heads/mb
 '
 
 test_expect_success 'git branch HEAD should fail' '
@@ -78,14 +81,14 @@ EOF
 test_expect_success 'git branch --create-reflog d/e/f should create a branch and a log' '
 	GIT_COMMITTER_DATE="2005-05-26 23:30" \
 	git -c core.logallrefupdates=false branch --create-reflog d/e/f &&
-	test_path_is_file .git/refs/heads/d/e/f &&
+	test_ref_exists refs/heads/d/e/f &&
 	test_path_is_file .git/logs/refs/heads/d/e/f &&
 	test_cmp expect .git/logs/refs/heads/d/e/f
 '
 
 test_expect_success 'git branch -d d/e/f should delete a branch and a log' '
 	git branch -d d/e/f &&
-	test_path_is_missing .git/refs/heads/d/e/f &&
+	test_ref_missing refs/heads/d/e/f &&
 	test_must_fail git reflog exists refs/heads/d/e/f
 '
 
@@ -213,7 +216,7 @@ test_expect_success 'git branch -M should leave orphaned HEAD alone' '
 		test_commit initial &&
 		git checkout --orphan lonely &&
 		grep lonely .git/HEAD &&
-		test_path_is_missing .git/refs/head/lonely &&
+		test_ref_missing refs/head/lonely &&
 		git branch -M main mistress &&
 		grep lonely .git/HEAD
 	)
@@ -799,8 +802,8 @@ test_expect_success 'deleting a symref' '
 	git symbolic-ref refs/heads/symref refs/heads/target &&
 	echo "Deleted branch symref (was refs/heads/target)." >expect &&
 	git branch -d symref >actual &&
-	test_path_is_file .git/refs/heads/target &&
+	test_ref_exists refs/heads/target &&
-	test_path_is_missing .git/refs/heads/symref &&
+	test_ref_missing refs/heads/symref &&
 	test_cmp expect actual
 '
 
@@ -809,16 +812,16 @@ test_expect_success 'deleting a dangling symref' '
 	test_path_is_file .git/refs/heads/dangling-symref &&
 	echo "Deleted branch dangling-symref (was nowhere)." >expect &&
 	git branch -d dangling-symref >actual &&
-	test_path_is_missing .git/refs/heads/dangling-symref &&
+	test_ref_missing refs/heads/dangling-symref &&
 	test_cmp expect actual
 '
 
 test_expect_success 'deleting a self-referential symref' '
 	git symbolic-ref refs/heads/self-reference refs/heads/self-reference &&
-	test_path_is_file .git/refs/heads/self-reference &&
+	test_ref_exists refs/heads/self-reference &&
 	echo "Deleted branch self-reference (was refs/heads/self-reference)." >expect &&
 	git branch -d self-reference >actual &&
-	test_path_is_missing .git/refs/heads/self-reference &&
+	test_ref_missing refs/heads/self-reference &&
 	test_cmp expect actual
 '
 
@@ -826,8 +829,8 @@ test_expect_success 'renaming a symref is not allowed' '
 	git symbolic-ref refs/heads/topic refs/heads/main &&
 	test_must_fail git branch -m topic new-topic &&
 	git symbolic-ref refs/heads/topic &&
-	test_path_is_file .git/refs/heads/main &&
+	test_ref_exists refs/heads/main &&
-	test_path_is_missing .git/refs/heads/new-topic
+	test_ref_missing refs/heads/new-topic
 '
 
 test_expect_success SYMLINKS 'git branch -m u v should fail when the reflog for u is a symlink' '
@@ -1142,7 +1145,7 @@ EOF
 test_expect_success 'git checkout -b g/h/i -l should create a branch and a log' '
 	GIT_COMMITTER_DATE="2005-05-26 23:30" \
 	git checkout -b g/h/i -l main &&
-	test_path_is_file .git/refs/heads/g/h/i &&
+	test_ref_exists refs/heads/g/h/i &&
 	test_path_is_file .git/logs/refs/heads/g/h/i &&
 	test_cmp expect .git/logs/refs/heads/g/h/i
 '

t/t5521-pull-options.sh

@@ -143,7 +143,7 @@ test_expect_success 'git pull --dry-run' '
 		cd clonedry &&
 		git pull --dry-run ../parent &&
 		test_path_is_missing .git/FETCH_HEAD &&
-		test_path_is_missing .git/refs/heads/main &&
+		test_ref_missing refs/heads/main &&
 		test_path_is_missing .git/index &&
 		test_path_is_missing file
 	)
@@ -157,7 +157,7 @@ test_expect_success 'git pull --all --dry-run' '
 		git remote add origin ../parent &&
 		git pull --all --dry-run &&
 		test_path_is_missing .git/FETCH_HEAD &&
-		test_path_is_missing .git/refs/remotes/origin/main &&
+		test_ref_missing refs/remotes/origin/main &&
 		test_path_is_missing .git/index &&
 		test_path_is_missing file
 	)

t/t5605-clone-local.sh

@@ -69,7 +69,7 @@ test_expect_success 'local clone of repo with nonexistent ref in HEAD' '
 	git clone a d &&
 	(cd d &&
 	git fetch &&
-	test ! -e .git/refs/remotes/origin/HEAD)
+	test_ref_missing refs/remotes/origin/HEAD)
 '
 
 test_expect_success 'bundle clone without .bundle suffix' '

t/test-lib-functions.sh

@@ -251,6 +251,61 @@ debug () {
 	done
 }
 
+# Usage: test_ref_exists [options] <ref>
+#
+#   -C <dir>:
+#      Run all git commands in directory <dir>
+#
+# This helper function checks whether a reference exists. Symrefs or object IDs
+# will not be resolved. Can be used to check references with bad names.
+test_ref_exists () {
+	local indir=
+
+	while test $# != 0
+	do
+		case "$1" in
+		-C)
+			indir="$2"
+			shift
+			;;
+		*)
+			break
+			;;
+		esac
+		shift
+	done &&
+
+	indir=${indir:+"$indir"/} &&
+
+	if test "$#" != 1
+	then
+		BUG "expected exactly one reference"
+	fi &&
+
+	git ${indir:+ -C "$indir"} show-ref --exists "$1"
+}
+
+# Behaves the same as test_ref_exists, except that it checks for the absence of
+# a reference. This is preferable to `! test_ref_exists` as this function is
+# able to distinguish actually-missing references from other, generic errors.
+test_ref_missing () {
+	test_ref_exists "$@"
+	case "$?" in
+	2)
+		# This is the good case.
+		return 0
+		;;
+	0)
+		echo >&4 "test_ref_missing: reference exists"
+		return 1
+		;;
+	*)
+		echo >&4 "test_ref_missing: generic error"
+		return 1
+		;;
+	esac
+}
+
 # Usage: test_commit [options] <message> [<file> [<contents> [<tag>]]]
 #   -C <dir>:
 #	Run all git commands in directory <dir>